Conspiracy theories are spreading faster than ever and causing real damage to America, says journalist Jonathan Kay. His new book, Among the Truthers, describes' his two-year "journey through America's growing conspiracist underground." Part of the book explains conspiracism historically – as a reaction, in part, to big national traumas, like wars or assassinations; but the heart of the book, a section titled "Why They Believe," looks into the psychology of conspiracism – that is, what makes individuals believe seemingly nutjob theories. He comes up with a field guide that breaks conspiracy theorists down into eight distinct types, as you'll see in the following slides.